TCM1520A

• On-Chip 150-V Bridge Diode Configuration
• Reliable BIDFET† Technology
• High Standby Impedance . . . 1 MW Typ
• Efficient High-Voltage Operation
• Output Compatible With TTL, NMOS, and CMOS
• Built-In 5-V Series Regulator
• Built-In Lightning and Transient Protection

Continuous supply voltage at C FILTER (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 V
Continuous differential input voltage, V_ID (AC INPUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 V
Continuous output current at 5-V OUTPUT, I_O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 mA
Continuous SCR on-state input current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 mA
SCR on-state input current, I_I(on) (duration 3200 ms) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 mA
Continuous total dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .See Dissipation Rating Table
Operating free-air temperature range, T_A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40°C to 105
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40°C to 125
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260

† Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended perating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

NOTE 1: All voltage values, unless otherwise noted, are with respect to COMMON (pin 7).

The TCM1520A is a monolithic ring-detection integrated circuit designed for use in isolated or nonisolated telephone applications. The device uses a modified form of the Texas Instruments BIDFET† technology to combine low-voltage CMOS and high-voltage bipolar input/output circuitry. It features efficient high-voltage (40 V to 150 V) operation with a typical current drain of 1 mA.

During standby, the input impedance is approximately 1 MW or greater, which prevents any interference with parallel off-hook telephones transmitting DTMF or voice frequencies. The TCM1520A achieves this high input impedance with an on-chip series zener diode that does not conduct until the voltage across AC INPUT (pins 1 and 8) exceeds 8 V. When the voltage across pins 1 and 8 exceeds 18 V, the internal switch is closed, which bypasses the 6.8-V zener diode series resistor. This allows more efficient power transfer to the load when the device is in the operating mode. In the operating mode, the impedance of the device varies from 30 kW to 7 kW over the ring signal of 40 V at 16 Hz to 150 V at 68 Hz and is reasonably independent of the output load.

In typical telephone applications, the TCM1520A is activated through the telephone line by a ring voltage of 40 V at 16 Hz to 150 V at 68 Hz. The TCM1520A generates a signal suitable to drive an optocoupler or TTL, NMOS, or CMOS logic. The 5-V OUTPUT can be used as a supply source for optocouplers or low-power logic. This output is noninverting and is at a high level during ringing.

The TCM1520A incorporates lightning and transient protection that is designed to withstand lightning strikes of 1.5-kV amplitude and 200-ms duration and also features built-in circuitry to avoid tapping or false triggering due to transients.